Intermittent-inductive train control



I 1,619,730 March 1, w. K HOWE INTERMITTENT INDUCTIVE TRAIN CONTROL Filed April 8, 1925 F'IGJ.

Ill)

Patented Mar. 1, 1927.

UNITED STATES Parent crates.

WINTER/OP K. HOWE, CF ROCHESTER, NEW" YORK, ASSIGNOE TO GENERAL RAILWAY SIGNAL COMPANY, OF ROCHESTER, NEW YORK.-

INTERMI'ITENT-INDUCTIVE TRAIN CONTROL.

Application .filed. April 8, 1925. Serial No. 21,597.

This invention relates to automatic train control systems of the intermittent inductive type, and more particularly to intermittent influence communicating devices for such systems. i

In certain well known systems of interm1ttent inductive trainncontroh. control influences are transmitted from a trackway to a moving vehicle by diverting ,fiHX emitted from a flux producing coil carried by thecar to a secondary or influence receiving coil dis? posed adjacentto. such flux producing; coil when a car-carried core containing these coils passes by atrackway-device comprising an inert or nonrmagnetized body. In practice this body has a bucking coil associated therewith and is active to divert flux in the manner mentioned it this bucking coil is open circuited, but is inactive when thiscoil is closed. in a circuit of: low, resistance. In practice, it has rbeen rfound that influence communicating arrangements of this kind have certain outstandingadvantages; One of these advantages resides in the fact that the voltage induced inthe secondary coil in this manner is dependenton the speed at which the train is moving, so that, a much higher voltage is induced at higher speeds, which is desirable in that the time duringwhich the current may act upon a suitable electro-responsive device at the higher train speeds decreases; wherebythe. net result is that ahighvoltage is induced when the time during which it may act is short and an et-- fective control influence may be transmitted through a range, of speedsfrom a certain low speed below which, it is ditlicult-to transmit aneffective control influence to the highest speed at which trains may run in. practice.

The present invention relates more particularly to systems Of: the kind mentioned modified to an extent whereby movement of the train is simulated by varying the flux emitted from the flux producing; coil.v This is accomplished by impressing an alternating current upon the primary coil so that a change of fluxtakes place at all speeds and evenwhen the vehicle is standing! still, More particularly, it is proposed. in accordance with the present invention to connect an alternating current source of energy in: series with the direct current source used in previous systems of this kind, so that, a pulsating current is applied to the primary coil and to the control relay instead of a continuous direct current.

Other objects, purposes and characteristic features of the invention will'appear as the description thereof progresses.

In describing the invention in detail re1terence will be made to the accompanying drawings in which Fig. 1 illustrates a simple type of block signalling system upon which the trackway apparatus of the train control system em bodying the present invention is superimposed; and

2 illustrates diagrammatically the car-carried apparatus embodying the present invention and shows a side elevation of a trackway device adapted to cooperate with this car-carried apparatus.

Track way appamtus.-The traekway apparatus adaptahlefor use with the car-carried apparatus illustrated has been shown in Fig. 1 and consists of a simple type of block signal system upon which suitable influence transmitting; trackway devices are superimposed together with means for. controlling the same.

Referring to Fig. l the track rails 1 are divided by insulating joints 2 into blocks in the usual manner, the blockI and the acent ends of two other blocks H and J hav ing been shown. Since the various blocks so are the same, like parts of each block are designated by like reference characters having distinctive exponent-s. At the entrance end of the block I is provided a track relay 3, which under normal clear traflic conditions of this block is energized by current flowing through the track rails of this block and derived from a track battery 4: at the exit end ofthe block, the normal direction of trafiic being as indicated by the arrow, this circuit thus constituting the usual closedtrack circuit. Near the entrance end of the block I is provided a line relay 5'which under normal clear traffic conditions of the block Iand the block J next in advance is energized through a circuit including the front contact 6 of the track relay 3 and the front contact 7 of the track relay 3 Although the influence communicating, 105 means embodying the present 'inventi on may be applied to train control systemsin which cab signals areused and in which wayside signals. arenot absolutely necessary, it may be used in connection with wayside signals of either the color light or semaphore type, and semaphore signals Z have for convenience been shown conventionally without illustrating their operating mechanism or control circuits. The apparatus thus far described it that used in practically every modern block signal system.

In addition to this apparatus there is provided at the entrance to the block I a track element T comprising a U-shaped core 9 preferably constructed of laminated magnetic material terminating in enlarged pole pieces 10 and having a coil 11 thereon which is normally closed in a circuit of low resistance through the front contact 12 of the line relay 5. This track element T is preferably located a distance in the rear of the entrance end of the block I, so that it is encountered by a suitable car-carried device of a train before the first axle of the train enters this block, this to avoid the train stopping itself, so to speak, by dropping the track relay of this block and placing the device T in its active condition before the car element has passed the same.

It is believed unnecessary to consider in I detail the movements of trains in the various blocks, it being obvious from the drawings that the track element T has its coil 11 closed in a circuit of low resistance. and 13 therefore inactive, when the block I at the entrance to which it is placed and the block next in advance of this block are unoccupied, and that it has its coil open-circuited when either of these blocks is occupied; so that, this trackway device T is inactive under clear traflic conditions ahead and is ac tive under both caution and danger tiaiiic conditions ahead. This control for the trackway device T should be borne in mind in connection with the description of the operation of the car-carried apparatus de scribed hereinafter.

Gar-carried appamiua-$ince the pres ent invention relates particularly to influence communicating means for train control systems it is considered unnecessary to show specific means for limiting the speed of the train or for effecting a brake application regardless of speed, and in order to show a simple device actually capable of controlling a train an electro-responsive device EPV has been illustrated, which may be assumed to be a device for effecting an automatic brake application either by controlling a suitable brake pipe venting device or a brake valve actuator or means for initiating a suitable speed restricting mechanism. This device EPV is preferably so constructed that it may be energized by direct current having an alternating current ripple impressed thereon.

In the arrangement shown in Fig. 2 the car element L comprises a core 15 of inverted U-shape preferably constructed of laminated magnetic material and terminating in downwardly facing pole pieces 16. The leading leg of this core 15 has a primary coil P contained thereon and the trailing leg is provided with a secondary coil S. This primary coil P is energized by pulsating current through a circuit includng the winding of an alternating current generator A0, a direct current source of energy such as the battery 18, a front contact 19 of a suitable control relay CR and the winding of the device EPV, this device EPV being contained in this circuit so that either a partial or total failure of the current for-energizing the primary coil P causes de-energization of this device EPV and a restriction in the movement of the train. The maximum or peak voltage of the generator AC is preferably lessthan that of the voltage V of battery 18, so that the resultant current is unidirectional.

The control relay CR preferably comprises a well constructed relay which has its moving parts well balanced and pivotally supported about a Vertical axis so that it is practically immune to jars and vibrations commonly experienced on railway trains. This control relay CE is connected in a stick circuit including a front contact 20 of this relay, the secondary coil S and the sources of energy 18 and AG in series. From this it will readily appear that momentary deenergization of or retraction of the contacts of the control relay CR interrupts the stick circuit for this device. so that it assumes its retracted position until restored by some other means.

0pemt z'ou.As heretofore mentioned the track element T may be in its active or inactive condition depending on traffic conditions ahead. Let us now assume that a train equipped with the car-carried apparatus shown in Fig. 2 in its normal condition passes over a track element T at a comparatively hi, h speed. with the coil 11 of this track element open circuited because traffic conditions ahead are dangerous. As the car element L comes into communicating relation with the track element T a sudden increase of flux occurs, this flux o a certain extent being due to diversion of flux from leakage paths into the secondary coil S and to a certain extent to the increase of flux through primary coil P by reason of the reduction of the reluctance of the magnetic circuit including the cores of the car and track elements L and T. This sudden iu- 'TPZISG of flux. the rate of increase of which is primarily due to the speed of the train, induces a voltage in the circuit including the control CR which is in a direction to oppose the voltage of the battery 18 and in practice is suiiicicnt to de-energize the control relay OR to an extent to drop its front tirally prevents contacts,.therebyopening the stick circuit torrthis relay and leaving it in its retracted position. WVith thecontrol relayCR in its retracted position the troutcoutactlt) of this relay opens thereby de-energizing the train control device EPV. As the car. element recedes fronrthe track elementLthe magnetic flux. again changes to normal. which induces a voltage invthe opposite direction in said secondary coil; this however produces no effect-since the secondaryncircuit is nowopen. Proceeding on the assumption that this-device EPV efl'ects an automatic brake application, rather than a reduction in speed only, the de-energization ot'relay CR causes the train to he brought toastop- In order that the trainmayagain proceed the engineeris required .to alight from the train and operate the reset push button 21, which is only accessible by a man standing on the ground. Depression of this push button closes a pick up circuit for the control 'relay CR which is the same as the stick circuit except that the stick circuit 20 of this relay is shunted by the normally open contact 22 of the push button 21. \Vith the control relay CR once energized the train may again proceed unrestricted. be noted that the reset push button 21 cannot-'he permanently held in its depressed position by'blocking or tying it down because it this were donethe-normallyclosed contact 23 included in thecircuit for the device EPV would be left open and the train could not proceed at all, so that this push button 21 isprotectecl against misuse and cannot be used 'to defeat the purpose of the system by making the control relay CR nonstick.-

By reviewing the operation of the system when passing an active trackway device at high speed, whichKwas just given, it will be noted that the primary coil P and the secondary coil S are so arranged on= the core 11 that their magneto-motive forces are cumulative. This, of course, is also true ot'the alternating current magneto-motive forces due to alternating current flowing in these circuits. In practice, theva-rious parts areso designed and proportioned that the alternating current flowing in the circuit including the primary nitude that the voltage induced in the secondary coil S by the primarycoil P practhe secondary circuit including the secondary coil S and the control relay CR due to the alternating current potential of the source AG in series in this secondary circuit. Net. it is proposed that a comparatively large pulsating current flows in the primary circuit including the primary oil Pand that a substantially constantdirect curreut oi rather-low value only flows in the secondarycircuit including the second- It should coil P is of such a mag any current from flowing in my coil- S, this constant; direct current being just sufficient to maintain the control relay CR energized when the car elementzL is disposed in air. there being practically no alternating current component in this sec ondary circuit.

Let us now assume that the train equipped with the apparatus shown in Fig. 2 in its normal condition passes onto a track element T with its coil 11 open circuited when moving at a comparatively low speed of say, A; mile per hour. Since the train is moving at this low speed the rate of change of flui; due to a reduction in the reluctance in the magnetic circuit including the car-carried core 15 is extremely low and probably insutlicient to drop the control relay CR. On the other hand, the alternating component of the pulsating current flowing in the primary coil P by reason of the improved iu ductive coupling or transformer connection between the primary coil P and the second ary coil S on account of the presence of the track element T causes a larger alternating current potential to beinduced inthesecondary coil S which is sufiicient during one wave of a cycle of alternating current. which wave is in a direction to oppose the battery 18 to tie-energize the control relay CR. With the control relay CR once de-ener-gized the train is brought to a stop as heretofore described, so that, the engineer must again alight to the ground and reset the apparatus to normal by depressing the pushbutton 2-1.

Having now considered the operation of this system under dangerous tra-fiic conditions when the train is moving at-a high speed and when it is moving at an extremely low speed, let us now consider the operation of this system when the car-carried apparatus moves by a trackwaydevice in its inactive condition and having its coil 11 closed in a circuit of low resistance As the car element- L moves onto the track element T. a very slow increase ot fiuxthrough the track element T takes place, regardless ofwhether this increase o'f-fiux is due to-th'e movement of'the train or due to the variation of the current flowing in the coilP. This slow change of flux through'the track element T, it is believed, is due to the bucking action of the coil 11.- because a slight in-= crease of flux through this track element T causes a comparatively heavy current to be set up in the bucking coil '11 due to this in crease of flux which, current is in a direction to oppose-a further change of flux. In other words, the bucking action of the coil 11 bucks back, so to speak, any change of flux tending to take place through" this track element; so that, the reluctance of the magiGlIlG circuit including the car element Lt whether it passes over this trackgelement at alow or at a high speed with the track element in its inactive condition is;not ma1 terially changed, and the control relay GR is not de-energized.

aving thus shown and described an i11- fluence communicating means for automatic train control systems of a type in which the strength of the inductive influence transmitted from the track to the vehicle increases with the speed, so that a car carried electroresponsive device may respond to such influences when a train is moving at a high speed as well as at the lower speeds in spite of the fact that the time during which such device may respond decreases as the speed goes up, and having disclosed a system in which movement of the train is simulated by the'provision of a source of alternating current which causes a certain change of flux to take place even when a train is standing still. it is desired to be understood that the particular arrangement shown illustrates only one way in which this may be accomplished' and has been shown for the purpose of simplifying the description of the invention rather than to illustrate the particular apparatus preferably employed in practice, and that various changes and additions may be made to meet the various requirements encountered in practice without departing from the spirit of the invention or the idea of means underlying the same.

hat is desired to be secured by Letters Patent is V I 1. Influence communicati11g means for antomatic train control systems of the intermittent inductive type comprising, a car ele ment having a primary and a secondary coil thereon, a direct current and an alternating current source of energy connected in series for energizing said primary coil, a secondary influence receiving coil, and means governed in accordance with traffic conditions ahead for causing the induction of a voltage in said receiving coil in response to flux emitted from said primary coil, whereby voltage is induced in the secondary coil by constant flux and movement of the vehicle by said means or is induced by varying flux alone.

2. Influence communicating means for automatic train control systems of the intermittent inductive type comprising; a car carried influence receiving element including a core of laminated magnetic material of general inverted Ushape; a primary coil on one leg of said core and a secondary 0011 on the other leg; a stick relay; an alternating current source of energy for energizing said primary coil :v a direct current source of energy; a circuit including in series said secondary coil, said stick relay and said source of direct current; and trackway means for effecting an inductive coupling between said primary and said secondary coil.

3- Influence communicating means for automatic train control systems of the intermittent inductive type comprising; a carcarried influence receiving element includmg a core of laminated magnetic material of general inverted U-shape; a primary coil on one leg of said core and a secondary coil on the other leg; a stick relay; a secondary circuit including said stick relay and said secondary coil in series; a direct current source of energy for energizingsaid secondary circuit; an alternating source of energy; and a circuit including said primary coil, said source of direct current and said source of alternating current in series.

4. In an automatic train control system; the combination of car-carried apparatus including a core having a primary flux pro ducing coil and a secondary influence receiving coil thereon; a control relay of the stick type; a direct current source of energy; an alternating current source of energy; a circuit including said primary coil and said two sources of energy in series; and a secondary circuit including said secondary coil, said control relay ant. said two sources of energy in series; and of trackway means for inductively coupling said primary and said secondary coil under adverse tratfic conditions ahead.

5. Means for inductively communicating influences from the trackway to a moving vehicle of a railway system at selected control points along the trackway comprisin carcarried apparatus including a source of pulsating electro-motive force; a control relay having a front contact connected in series with its winding; an influence receiving element comprising a core having a primary and a secondary winding thereon; a secondary circuit including said secondary winding, said control relay and said source of electromotive force in series; and a primary circuit including said primary winding and said source of electro-motive force in series, the source of electro-motive force being so connected in said two mentioned circuits that the varying voltage induced in said secondary winding by flux emitted from said primary winding is in a direction to oppose the varying voltage impressed upon said secondary circuit.

6. Car-carried apparatus for automatic train control systems comprising. a core located in inductive relation with the trackway, a primary coil on said core, a secondary coil on said core, and separate circuits for energizing said coils and each including the; same source of alternating current. the number of turns in said coils being so proportioned that the voltage induced in said secondary coil by flux emitted by said primary coil is substantially equal to the voltage of said alternating current source.

7. Influence communicating means for antomatic train control systems oi the intermittent inductive type comprising: a primary coil; a secondary coil; a stick relay; an

alternating current source of energy for energizing said primary coil; a direct current source of energy; a circuit including in series said secondary coil, said stick relay and said source of direct current; and trackway means for effecting an inductive coupling between said primary and said secondary coils.

8. Influence communicating means for automatic train control systems of the intermittent inductive type comprising: a primary coil, a secondary coil; a stick relay; a secondary circuit including said stick relay and said secondary coil in series; a direct current source of energ Y for energizing said secondary circuit; a source of alternating current; and a circuit including said primary coil, said source of direct current and said source of alternating current in series.

9. An automatic train control system comprising a primary flux producing coil; a secondary influence receiving coil; a control relay of the stick type having a front stick contact closed when the relay is energized; a direct current source of energy; an alternating current source of energy; a circuit including said primary coil and said two sources of energy in series; a circuit including said secondary coil, said control relay, its front contact and said two sources of energy in series; and trackway means for inductively coupling said primary and said secondary coil under adverse traflic conditions ahead.

10. Means for inductively communicating influences from the trackway to the moving vehicle of a railway system at selected control points along the trackway comprising: car-carried apparatus including a source of pulsating electromotive force; a control relay having a front contact connected in series with its winding; 21 primary winding; a secondary winding; a secondary circuit including said secondary winding, said control relay, its front contact and said source of electro-motive force in series; and a primary circuit including said primary winding and said source of electro-motive force in series; the sources of electro-motive force being so connected in said two mentioned circuits that the varying voltage induced in said secondary winding by fluX emitted from said primary winding is in a direction to oppose the varying voltage impressed. upon said secondary circuit.

11. Car-carried apparatus for automatic train control systems comprising, a primary coil, a secondary coil, and separate circuits for energizing said coils and each including the same source of alternating current, the number of turns in said coils being so proportioned that the voltage induced in said secondary coil by fluX emitted by said primary coil is substantially equal to the volt age of said alternating current source.

In testimony whereof I afiix my signature.

WINTHROP K. HOWE. 

